1. Technical Field
The present invention relates to a liquid droplet discharging apparatus capable of drawing by discharging droplets of a liquid on a target object, a method for discharging a liquid, a method for producing a color filter by using the discharging apparatus and the liquid discharging method, and a method for producing an organic EL device.
2. Related Art
Recently, much attention has been paid on production of various functional devices by discharging droplets of a functional-material containing liquid on a target object such as a substrate, using a liquid droplet discharging method. Typical functional devices are color filters, organic electro luminescence (EL) elements, and the like.
For production of the functional devices, one critical issue is to form a homogeneous and even functional film on the target object to obtain desired characteristics. To solve the issue, there is disclosed a method for producing a color filter in JP-A-2002-221616 (p. 5) (a first example of related art). The disclosed method includes moving a substrate relatively with respect to inkjet heads each having a nozzle line formed by linearly arranging a plurality of nozzles and divided into a plurality of nozzle-line groups and discharging a filter material selectively from the nozzles to form a filter element on the substrate.
The color filter producing method includes moving either one of the inkjet heads or the substrate relatively with respect to the other one of the heads or the substrate to perform sub-scanning such that at least a part of the nozzle-line groups can scan the same part of the substrate in a main-scanning direction. Thereby, even if an amount of ink discharged varies among the nozzles, the ink as the filter material is discharged from nozzles belonging to different nozzle-line groups. This can prevent unevenness of film thickness among the filter elements. In short, the above color filter production method allows variation of discharge amount among the nozzles to be distributed among the nozzles.
As a liquid droplet discharging apparatus capable of discharging a plurality of kinds of liquids, there is known a liquid droplet discharging apparatus disclosed in JP-A-2006-346575 (p. 5) (a second example of related art). The disclosed apparatus includes a carriage having a plurality of liquid droplet discharging heads each discharging a different kind of liquid; a moving unit moving the discharging heads relatively with respect to a workpiece in a main-scanning direction and a sub-scanning direction in a state in which the discharging heads face the workpiece; and a drawing control unit selectively driving the discharging heads to allow the heads to discharge a plurality of kinds of liquids on the workpiece in sync with main scanning by the discharging heads and the workpiece.
In the carriage, nozzle lines of the discharging heads are arranged in the sub-scanning direction and end positions of nozzle lines discharging different kinds of liquids are deviated from each other. Thus, it is disclosed that the above arrangement can reduce streaky discharge unevenness in the main-scanning direction due to variation of discharge amount at ends of the nozzle lines.
On the other hand, as a color filter as a functional device, there is proposed a color filter having a filter element with multiple colors (six colors) to improve color reproducibility in JP-A-2005-62833 (a third example of related art).
It can be considered that the color filter production method of the third example of the related art applies the color filter production method of the first example thereof and a structure of the discharging apparatus of the second example thereof. If the carriage includes a plurality of liquid droplet discharging heads capable of discharging the same kind of a liquid, the carriage becomes larger along with an increase in kinds of liquids. Consequently, the liquid droplet discharging apparatus becomes larger.
Meanwhile, when a total number of the discharging heads mounted is equal to that of the kinds of the liquids, the carriage can be made into a smaller size, whereas the liquids are discharged under influence of discharging characteristics inherent to the respective heads. As a result, there occurs a difference of discharge condition among the liquids, which can be recognized as discharge unevenness.